The present invention relates to a head supporting mechanism portion of a magnetic disc apparatus, and particularly to a head supporting apparatus in which an IC chip is mounted on an arm portion thereof and a magnetic disc apparatus using such a head supporting apparatus.
In the conventional magnetic disc apparatus, when improving a transfer speed an impedance reduction occurs in a wire extending from a read/write IC for controlling read/write signals to a magnetic read/write head. When the impedance reduction occurs, a distortion is generated in the signal and it is impossible to accurately read/write from or to the magnetic disc. Then, it is necessary to mount the read/write IC for amplifying the read/write signal as close to the magnetic head as possible.
Then, in JP-A-3-187295, there is disclosed a structure such that the read/write IC is directly mounted on the arm portion for supporting the magnetic head.
In this structure, heat radiating fins are formed in an arm portion (suspension) for supporting the head, thereby radiating heat from the read/write IC.
In the arm portion for supporting the magnetic head, it is necessary to make the mass thereof as light as possible and to make the moment of inertia thereof as small as possible for performing a high speed seeking operation. Further, in order to accurately position the magnetic head, the arm portion requires a suitable rigidity and should be substantially vibration proof. Accordingly, it is necessary to employ a compact and light weight IC for the read/write IC to be mounted on the arm portion for supporting the magnetic head on the other hand, it is necessary to make the magnetic head also compact and particularly it is necessary to supply a large amount of electric power at a time of writing information. As a result, since the read/write IC mounted on the arm for supporting the magnetic head consumes a large amount of electric power with a little volume, a temperature of the IC itself becomes very high is and there is a possibility that a thermal fracture will occur. Therefore, it is necessary to radiate the heat of the IC.
In the case of a structure for radiating the heat of the read/write IC by means of the radiating fins provided in the arm portion for supporting the head, there are the following problems.
Firstly, the arm portion for supporting the head is designed so as to make it compact and light, and therefore, when the heat is directly radiated to the arm portion, the arm itself is deformed due to a thermal expansion. As a result, an angle of attitude of the head is changed and a positioning accuracy is deteriorated Accordingly, the IC is mounted near a root portion of the arm where the thermal expansion of the arm can be ignored. However, this structure limits the degree to which the wire between the read/write IC and magnetic head can be shortened and thus runs counter to an original object thereof.
Firstly, the arm portion for supporting the head is designed so as to make it compact and light, and therefore, when the heat is directly radiated to the arm portion, the arm itself is deformed due to a thermal expansion. As a result, an angle of attitude of the head is changed and a positioning accuracy is deteriorated. Accordingly, the IC is mounted near a root portion of the arm where the thermal expansion of the arm can be ignored. However, in this structure, it is limited to shorten the wire between the read/write IC and the magnetic head which is an original object.
As mentioned above, in accordance with the conventional method of radiating the heat of the read/write IC by means of the radiating fins provided in the arm portion for supporting the magnetic head, there is a problem that the positioning accuracy of the magnetic head is deteriorated due to the deformation caused by the thermal expansion of the arm itself.
Accordingly, an object of the present invention is to provide a head supporting apparatus which is structured so as to mount a read/write IC in an arm portion for supporting a head, radiate the heat of the read/write IC and generate no thermal expansion of the arm itself, and can be easily mounted.
In the head supporting apparatus of the present invention, a read/write IC chip is mounted on a heat insulating substrate, and the heat insulating substrate is mounted on a suspension and a heat radiating plate is mounted on a surface of the IC chip opposite to a surface toward the heat insulating substrate.
Further, bent portions are provided in the heat radiating plate and a bent portion in an upstream side, in which an air flow resulting from rotation of a magnetic disc collides with the heat radiating plate, is made longer than a bent portion in a downstream side, whereby air turbulence associated with the rotation of the disc is prevented.